aureola

Science Dictionary
aureole   (ôr'ē-ōl')  Pronunciation Key 
  1. A band of metamorphic rock surrounding a body of cooled magma. Aureoles form through the process of contact metamorphism. See more at contact metamorphism.

  2. See corona.


American Heritage
Science Dictionary
corona   (kə-rō'nə)  Pronunciation Key 
Plural coronas or coronae (kə-rō'nē)
  1. The luminous, irregular envelope of gas outside the chromosphere of a star. The Sun's corona is composed of ionized gas between approximately 1,000,000°K and 2,000,000°K and has an extremely low density. This phenomenon is visible only during a solar eclipse.

  2. A faintly colored luminous ring appearing to surround a celestial body (such as the Moon or Sun) that is visible through a haze or thin cloud, caused by diffraction of light from suspended matter in the intervening medium. Also called aureole.

  3. A faint glow of the air in the region of very strong electric fields, caused by ionization of the air molecules and flow of current in that region in corona discharge.

  4. The crownlike upper portion of a bodily part or structure, such as the top of the head.

  5. A crown-shaped structure on the inner side of the petals of some flowers, such as the daffodil.


The American Heritage® Science Dictionary
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